So you often see a DC rating of 24VDC or 120VAC due to this behavior. I am using the following wiring: The output pin is connected to an Arduino-like microcontroller. MCR loop-powered isolator, 1-channel, for the electrical isolation of current signals without auxiliary power, with screw connection. I want to control a 5 V input on another device with a ESP8266 by using a PC817 opto-isolator. MINI MCR-SL-1CP-I-I - Loop-powered isolators. there are several different derating factors, but inductive loads are severe.Īnd DC use is usually more aggressive since metal migration only in one direction from point-to-point. I am looking for a relay with contact voltage rating in the range of 20-30 V and current rating in the range of 7-8 A so trying to. I generally don't bother with anything under a 10amp rated relay. There are other things to do enhance the longevity of the points, but those really should come into consideration after you apply a derating according to the type of load. Read the derating document attached, that is the guideline. In other words, for 1.8 amps of inductive load, you need a 4.5 amp or better rated relay. You may not like thiis answer, but the 'derating' factor for inductive loads which is normally applied to limit the current capacity of the relay to 40% of the advertised rating (motors derate down to 20%!). Is there something I can do to alleviate the contact arcing? The load solenoids do have snubber (free-wheel) diodes, BTW. Going through these relays at an alarming rate but they are a very small package that I can't simply replace due to limited space. We are right at 1.8A and switching at approximately every 5 seconds. These are name-brand relays (Phoenix Contact) and rated at 2A switching of an inductive 24v DC load (solenoid coil).
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